1. Technical Area
The present invention relates to a device and a method for removing an object from a moulding tool in connection with casting or moulding an object, wherein there is a retaining force between the moulding tool and the object.
Such a device may be used for removing objects in connection with different kinds of moulding and casting processes, for example injection moulding, vacuum forming, thermoforming, compression moulding, or blow moulding.
2. Prior Art
There are many known methods for forming an object. One category of forming methods have in common that they are based on a work-piece, which is heated until it becomes formable and is then formed by pressing the work-piece against a moulding tool having a surface of a shape, which determines the shape of the object to be formed. The work-piece is usually a sheet or a tube of plastic that is heated until it becomes soft enough to be formed. When the work-piece has reached the correct temperature, the object is formed by pressing the work-piece against a moulding tool so that the work-piece is formed after the surface of the moulding tool. Cooling of the object takes place in the moulding tool until the object is stable enough to allow to be moved for further processing. Examples of such forming methods are thermoforming, vacuum forming, compression moulding, or blow moulding.
Another method for forming objects is casting. At casting processes, the source material is heated until it melts and the object is formed by supplying a moulding tool comprising a moulding space, the shape of which corresponds to the shape of the object, with the liquid cast material. The moulding tool usually consists of two halves, wherein one side is movable and the other is fixed. The object is kept in the moulding tool until it is cool enough to allow further processing. The moulding tool is opened by moving the movable side aside and the object is picked out of the casting machine. Thereafter, the next object can be cast.
A problem in connection with casting and moulding of objects is that the object shrinks when it solidifies and gets stuck in the moulding tool. This means that, in some cases, it is necessary to use large forces to loosen the object from the moulding tool. This problem has, for example, been solved by providing the moulding tool with ejectors, for instance in the shape of pins, pushing the object and in such a way ejecting it out of the mould. To avoid deformation of the object by the ejectors, the object has to be kept in the moulding tool until it is solid enough. During casting processes producing large volumes, short cycle times are important for an optimal production and therefore it is desirable to remove the object as early as possible from the moulding tool.
It is also known with devices for moving the finished object from the moulding tool after the object has been released from the moulding tool. One such known device comprises a body provided with suction cups, which are coupled to the object. At first, the suction cups are coupled to the object and thereafter the object is released from the moulding tool by means of the ejectors. When the object is released, the device transports the object away from the moulding tool to a suitable place for further processing. Such a device cannot be used for releasing the object due to the fact that the suction cups may cause deformation of the object if it has not become entirely solidified.